Acoustic filtration

Industrial Pigments and solids can be easily dispersed in paint, inks and resins. Engineering articles are often cleaned and degreased by immersion in ultrasonic baths. Two less widely used applications are in acoustic filtration and metal casting. 

Water purification Electric fields - electro-acoustic filtration... 

Acoustic emission (AE) technique, in nondestructive evaluation, 17 425 Acoustic fields, filtration and, 11 324 Acoustic methods, of emulsion characterization, 10 128 Acoustic microscope, 16 505... 

G.L Eskin, Degassing, filtration, and grain refinement processes of light alloys in a field of acoustic cavitation. Advances in Sonochemistry, T.J. Mason (ed.), JAI Press, London, 1996, 4, 101-159. 

It is the subsequent fate of some of these bubbles, as they oscillate in the applied sinusoidal acoustic field, which is the origin of sonochemistry. However, before embarking upon a discussion of bubble dynamics let us consider what other factors apart from degassing, pressurising and filtration affect the onset of cavitation. 

Uses. Glasswool is used for thermal and acoustical insulation in construction and ship building for air filtration in furnaces and air-conditioning systems. 

A simplified particle-trajectory analysis has been used to explain the essential features of US-assisted filtration. Acoustic forces can cause particle trajectories to deviate from hydrodynamic pathlines towards particle collectors, thereby enhancing their collection efficiency in comparison to pure hydrodynamic interception. 

DEGASSING, FILTRATION, AND GRAIN REFINEMENT PROCESSES OF LIGHT ALLOYS IN A FIELD OF ACOUSTIC CAVITATION... 

Mechanism of Fine Filtration ofa Melt in a Field of Acoustic Cavitation. . 131... 

Irrespective of the conditions ensuring the abnormally rapid movement of a liquid in a capillary under acoustic cavitation effect, it is important to note that the sonocapillary effect follows all the major effects of the ultrasonic treatment of melts. Among such phenomena are wetting and activation of solid nonmetallic impurities in a liquid metal as well as fine filtration of a melt through porous filters under action of the ultrasonic cavitation treatment. For both processes, ultrasonic cavitation and sonocapillary effect with formation of cumulative jets provide the accelerated mass transfer of a melt to slots and cracks in the surface of nonwettable solid particles and into capillary channels of fine filters. 

Assuming that the melt flow is laminar, its flow rate through a multilayer filter does not depend on time. But in the case when a molten metal contains dispersed particles with a size less than the section of the channel, the flow rate becomes dependent on time mainly due to the adhesion of the particles to the channel walls. With this, those particles which have the size larger than that of the capillary channel section are retained at the entrance of the filter in a form of a cake which increases the apparent length of the channel and decreases the active surface of the filter. The input of intensive ultrasonic oscillations in the mode of developed cavitation results in the appearance of active acoustic streams near the filter surface and in washing-out the cake. In the ideal case, the value of the flow rate through the filter can be sustained constant for a sufficiently long period of fine filtration due to the action of acoustic cavitation and streams. 

Eskin, G.I. Mechanisms of Fine Filtration of Molten Metals in Acoustic Cavitation Field. Abstr. 2nd Meeting of European Soc. Sonochem. (ESS), Sept. 1991, Gargnano, Italy, 1991, pp. 62-63. 

PVDF has been used in foams. The potential applications include flame-resistant insulation filtration materials exterior decorative, acoustical, or insulation materials, etc. ... 

Recently developed cell retention devices such as alternating tangential filtration (ATF) or an acoustic device (Biosep) can be fitted to existing bioreactors at contract organizations. 

There are some excellent review articles on different aspects of mesostructured materials, such as synthesis, properties, and applications. " Extensive research effort has been devoted to the exploitation of new phases (lamellar, cubic, hexagonal structures), expansion of the pore sizes (about 2-50 nm are accessible), and variable framework compositions (from pure silica, through mixed metal oxides to purely metal oxide-based frameworks, and inorganic-organic hybrid mesostructures). Another research focus is on the formation of mesostructured materials in other morphologies than powders, e.g. monolithic materials and films, which are required for a variety of applications including, but not limited to, sensors (based on piezoelectric mass balances or surface acoustic wave devices), catalyst supports, (size- and shape-selective) filtration membranes or (opto)electronic devices. The current article is focused... 

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